Fire Emblem Fates: Two versions of the franchise’s new installment offer players an unprecedented choice: fight an opposing force or join the other side and try to make changes from within.

I was really hoping NoA would do away with this nonsense (separating the story into two games) but I guess we're stuck with it. I might hold out on this one on the hopes that we get some kind of combo-deal later on. who am I kidding I'll buy both

Here's an English trailer

Some (Japanese) new trailers showing off the faction's respective classes: